This disclosure relates to a system for monitoring the amount (mass, weight, concentration, etc.) of particulate matter (PM) within a vehicle's exhaust, or emissions. The system may be utilized on-board a vehicle to provide an accurate, differentiated PM measurement.
PM refers, generally, to matter suspended in a fluid (e.g., a gas) in the form of very small particles or droplets. The term exhaust (or, aerosol, exhaust gas, exhaust sample, etc.), refers to a fluid and the PM carried therein. PM is commonly emitted from engines and typically includes carbonaceous matter in elemental form (or, soot) and carbonaceous matter in the form of volatile and semi-volatile hydrocarbon compounds (which may be SOF, or soluble organic fraction), and other organic and inorganic compounds (such as sulfates).
Certain vehicles may be required to emit PM at a level below a predetermined threshold during government mandated emissions test procedures, including so called not-to-exceed measurement events (NTE events), or during normal use. The amount of PM expelled by such a vehicle under test is indicative of engine efficiency, fuel quality, vehicle pollution, etc. PM within exhaust can be collected by, or can stick to, a measurement filter through which the exhaust passes. In one known type of test, PM is monitored utilizing a measurement filter that collects substantially all PM within a sample of the vehicle's exhaust. The measurement filter is removed from the sampling apparatus and the amount of PM collected by the filter is determined in a laboratory, for example.